Apparatus for controlling fluid flow rate

Abstract

A variable infusion device for administering liquids parenterally to a patient is formed of inexpensive plastic members. The device includes an elongated passage defined between two members of the device which are bonded to one another. A third member is movable relative to the first and second members to change the length of the elongated passage through which liquid flows thereby changing the flow rate of the liquid through the device. The liquid flow rates to the patient can be incrementally adjusted over a wide range of flow rates. Settings also include a flow rate for merely keeping the patient's vein open.

I claim: 
     
       1. Apparatus for controlling a flow rate of a liquid to be administered parenterally to a patent, said apparatus comprising: a housing having spaced inlet and outlet channels for said liquid;   a first metering plate held against movement with respect to said housing, said plate having a front surface facing away from said housing and a rear surface facing said housing with a plurality of apertures extending between said front and rear surfaces, a first of said apertures being aligned with said inlet channel and a second of said apertures being aligned with said outlet channel;   plate means held against movement with respect to said housing and engaging the rear surface of said metering plate, said plate means having a first hole aligned with said inlet channel and said first aperture and a second hole aligned with said outlet channel and said second aperture, said rear surface of said metering plate and said plate means defining a first metering passage, one end of said passage communicating with one of said first and second apertures, the other end of said passage communicating with a third of said apertures, said plurality of apertures further comprising a series of apertures each of which communicates with said metering passage at spaced locations intermediate said ends; and   cover means supported by said housing and movable relative thereto, said cover means having an interior surface engaging the front surface of said metering plate, said interior surface having a groove one end of which is continually in alignment with the other of said first and said second apertures, said cover means being movable with respect to said housing selectively to bring the other end of said groove into alignment with any predetermined one of said series of apertures and said third aperture whereby movement of said cover means with respect to said housing incrementally changes the flow rate of said liquid between said channels by adding or bypassing portions of said metering passage through which said liquid must travel in flowing from said inlet channel to said outlet channel.   
     
     
       2. Apparatus for controlling a flow rate as set forth in claim 1 wherein said plate means comprises a baffle plate and a second metering plate, said baffle plate being held between said first and second metering plates, said baffle plate and said second metering plate defining a second metering passage, one end of said second metering passage communicating with said one of said first and second apertures, said first metering plate having an additional aperture extending between said front and read surfaces and said baffle plate having an additional hole aligned with said additional aperture and the other end of said second metering passage, said cover means being movable with respect to said housing to bring the other end of said groove into alignment with said additional aperture whereby the first metering passage is bypassed and said liquid must traverse said second metering passage in flowing from said inlet channel to said outlet channel. 
     
     
       3. Apparatus for controlling a flow rate as set forth in claim 2 wherein said second metering passage is configured to provide a lesser flow rate than the entirety of said first metering passage. 
     
     
       4. Apparatus for controlling a flow rate as set forth in claim 2 wherein said first and second metering plates and said baffle plate are bonded together. 
     
     
       5. Apparatus for controlling a flow rate as set forth in claim 1 wherein the rear surface of said first metering plate is substantially flat and has a metering groove, said metering groove and the facing surface of said plate means defining said first metering passage. 
     
     
       6. Apparatus for controlling flow rate as set forth in claim 5 wherein said metering groove is serpentine-shaped. 
     
     
       7. Apparatus for controlling a flow rate as set forth in claim 1 wherein said cover means is rotatably mounted with respect to said housing, said other of said first and second apertures being disposed along the axis of rotation of said cover means. 
     
     
       8. Apparatus for controlling a flow rate as set forth in claim 7 wherein the remaining apertures apart from said other aperture are arranged in a generally circular array about said other aperture.